The present invention relates to the sterilization arts. It finds particular application in conjunction with the sterilization of medical instruments and equipment. It will be appreciated, however, that the invention is also applicable to the microbial disinfection or sterilization of other articles such as food processing equipment, pharmaceutical processing equipment, animal cages, and other equipment.
Various methods and apparatus are known for sterilizing medical instruments and devices. For example, medical instruments and other devices are commonly sterilized in a steam autoclave. Autoclaves kill life forms with a combination of high temperature and high pressure. However, steam autoclaves have several drawbacks. The pressure vessels are bulky and heavy. Also, the high temperature and pressure tend to reduce the useful life of medical devices having rubber and plastic components. The medical devices must be pre-cleaned before being placed in the autoclave to remove post-operative bodily tissues and fluids. Moreover, the autoclave sterilization and cool-down cycles take an excessive amount of time, especially in light of the need to minimize the "down time" of expensive, reusable medical devices.
Another known sterilization method utilizes ethylene oxide gas. Ethylene oxide gas sterilization and aeration cycles are even longer than steam autoclave sterilization and cool-down cycles. Ethylene oxide is also hazardous to humans and, therefore, environmental concerns are associated with its use.
Low temperature liquid disinfection and sterilization devices are also known. These devices typically utilize one of several known liquid anti-microbial solutions such as peracetic acid, glutaraldehyde, alcohol, aqueous hydrogen peroxide, and the like. In general, these low temperature liquid systems have been found to be effective. However, hospitals and other health care facilities continue to demand improved sterilization effectiveness and efficiency to reduce the risk of infection and to reduce the percentage of time that expensive medical devices are out of use for sterilization procedures. Also, certain low temperature liquid anti-microbial solutions have fallen out of favor. For example, the use of glutaraldehyde presents environmental concerns and also requires an excessively long cycle time to sterilize, rather than simply disinfect, medical devices. The environmentally harmful glutaraldehyde must be specially disposed of, increasing the cost of sterilization. Alcohol has been found to be destructive to certain plastic components of medical instruments.
Recently, there has been an increased emphasis on the effective cleaning of post-operative debris from the medical instruments and devices. Most known sterilization equipment requires that the contaminated medical devices be precleaned before the sterilization cycle. Others simply sterilize without regard to cleaning which results in a sterile device having sterile debris adhered thereto.
Certain sterilization devices rely upon the filtering of water with a 0.2 .mu.m or smaller pore size microbe-removal filter media to provide a sterile rinse liquid. However, it would be desirable to provide an additional safeguard against the recontamination of medical devices with rinse liquid by ensuring a virus-free rinse solution. A virus-free rinse solution may not be assured with simple filtration of the rinse liquid. Therefore, there has been found a need to provide a sterilization apparatus that ensures a bacteria and virus free rinse liquid to prevent the accidental recontamination of the sterilized medical device during rinsing operations.
Most recently, the cleaning and decontamination properties of solutions formed via the electrolysis of water under special conditions have been explored. Electrolysis devices are known which receive a supply of tap water, commonly doped with a salt, and perform electrolysis on the water to produce two separate streams of fluid--(i) an anolyte produced at the anode of the electrolysis unit; and, (ii) and catholyte produced at the cathode of the electrolysis unit. The anolyte has been found to be free of all viable microbes, including viruses, and has also been found to have powerful anti-microbial properties, including anti-viral properties. The catholyte has been found to have excellent cleaning properties.
To create these anolyte and catholyte solutions, tap water, often with an added electrically conducting agent such as the salt sodium chloride, is passed through an electrolysis unit or module which has at least one anode chamber and at least one cathode chamber which may be separated from each other by a membrane. An anode contacts the water flowing in the anode chamber, while the cathode contacts the water flowing in the cathode chamber. The anode and cathode are connected across a source of electrical potential to expose the water to an electrical field. The membrane may allow the transfer of electron carrying species between the anode and the cathode but limits fluid transfer between the anode and cathode chambers. The salt and minerals naturally present in and/or added to the tap water undergo oxidation in the anode chamber and reduction in the cathode chamber. The solution resulting at the anode (anolyte) and the solution resulting at the cathode (catholyte) remain separate or are recombined and can be used for a wide variety of different purposes.
The present invention contemplates a new and improved sterilization apparatus for producing and utilizing anolyte and catholyte, as needed, to clean, disinfect or sterilize, and provide a sterile rinse for medical devices.